70 G. M. DAWSON KOCKY MOUNTAIN REGION IN CANADA 



the Laramide range in Canada, in which direction the conditions of dep- 

 osition appear to have been uniform. 



Rocks of the Carboniferous period are probably present in several 

 parts of the S3^stem of Gold ranges, but practically no paleontological 

 evidence of their existence has yet been obtained."^ 



Between these .mountains and the Coast ranges, however, the Carbon- 

 iferous is again well represented, but in a manner very different from that 

 found in the Laramide range, for although limestones are still important, 

 clastic rocks of various kinds, with great masses of contemporaneous 

 volcanic materials, preponderate. These rocks occup}^ a considerable 

 part of the Interior plateau of southern British Columbia, and run north- 

 westward, with practically identical characters, far into the Yukon dis- 

 trict, probably to the eastern boundary of Alaska and beyond. 



Fossils referable to the Carboniferous period are found sparingly in 

 association with them, particularly F'asullnx, and none of distinctively 

 older or more recent date have been discovered. At the same time, it is 

 not improbable that the series may include in its lower part beds older 

 than the Carboniferous, and ])ossible that its upper beds may be newer 

 than those of that system. Its constant characters, however, render it 

 approi)riate to attach a distinctive name to tlie series, which has conse- 

 quently been designated the Cache Creek series, with the understanding 

 that should any part of it subsequently be discovered to be separable 

 paleontologically, the name will be retained for the Carboniferous portion- 

 This name is, in fact, somewhat more important than a purely local one, 

 being intended to denote a peculiar development of the Carboniferous 

 system, well defined in its nature and characterizing a wide middle zone 

 in tlie northern part of tlie Cordilleran belt, but of which the upper and 

 lower limits still remain somewhat indefinite. 



The name is one of those of Selw3''n's i)reliminary classification, where 

 Lower and Upper Cache Creek groups are described, the term " Marble 

 Canyon limestones " being given as an alternative for the latter. The 

 division into lower and ui)per parts on lithological grounds is still rec- 

 ognized, but later investigations and the ])roved Carboniferous age of 

 both parts have since caused the whole to be referred to as a single great 

 group.f 



The composition and approximate thickness of the Cache Creek strata 

 are best known in the area of the Kamloops map-sheet, where it may 

 be briefly characterized as follows : The lower division consists of argil- 

 lites, generally as slates or schists, cherty quartzites or hornstones, vol- 



* Summary Reports, Geol. Surv. Can., 1895, p. 24 A ; 189G, p. 22 A ; 1897, p. 29 A. 

 tSee Report of Progress, Geol. Surv. Can., 1871-72, pp. 52, GO, Gl ; also Annual Report, Geol. 

 Surv. Can., vol. vii (N. S.), p. 32 B et seq. 



